Generally, writing tools are typically classified into fixed type writing tools, rotary type writing tools, knock type writing tools, and slide type writing tools. The fixed type writing tools are designed so that a cartridge is fixed and a cap is used to cover a nib. The rotary type writing tools are designed so that part of a cartridge moves along a spiral pipe to be projected out when part of a shaft is rotated. The knock type writing tools are designed so that a cartridge is projected out by a spring when part of a shaft is pressed. Further, the slide type writing tools are designed so that a cartridge slides to be retracted into and projected out of a shaft.
The slide type writing tools have an advantage in that it is unnecessary to open or close an additional cap. However, the slide type writing tools have a problem in that a nib hole is formed in an end of the writing tool, so that such a slide type structure may be limitedly applied only to non-volatile writing tools, such as oil-based ink, or to writing tools having low volatility.
Thus, writing tools having high volatility, for example, a marker pen, a correction pen, a roller ball pen, a highlighter, etc., must have caps, although it is inconvenient to open or close the caps. The reason why the writing tools having high volatility have the caps is that the ink of the nibs dries up when the nibs of the writing tools are exposed to the air, thus shortening the life spans of the writing tools.
In order to solve the problems, efforts have been made to develop a writing tool that prevents the ink of the writing tool, which is a liquid or a semi-liquid ink, or a volatile or non-volatile ink, from drying up, while protecting a nib of the writing tool.
In order to prevent a nib from drying up and protect the nib, Japanese Patent No. 1987-0012570 was proposed, and is entitled ‘capless writing tool having dryness prevention unit’. The writing tool disclosed in the document has a slide type structure. When a user presses a push-button of the writing tool once, a cover is opened so that a nib hole is opened by the tensile force of an elastic cord. Further, when the user presses the push-button one more time, the cover is closed, thus preventing ink from drying up.
However, the writing tool according to the cited document has problems in that it uses the tensile force of the elastic cord, so that the opening or closing of the cover is not rapidly executed, and it has low durability, and further, the ability of the cover to temporarily close and seal the nib hole is very poor.
In Korean Patent Appln. No. 10-2000-65693 there was proposed a ‘writing tool with inseparable elastic cap’. According to the cited document, the writing tool is provided with an elastic cap. The elastic cap has, at a predetermined position thereof, a cut slit through which a nib passes. Further, a predetermined portion of the elastic cap, which is opposite the cut slit, is in close contact with a guide groove of the writing tool. Thus, when the cap moves backward, the nib is exposed outside so that a user can write with the instrument. Conversely, when the cap moves forward, the cap prevents the ink from drying. The middle portion of the writing tool has the same shape as the body of a typical writing tool.
However, the writing tool according to Korean Patent Appln. No. 10-2000-65693 has a problem in that the portion around the cut slit may be stained with the ink of the nib, as the nib is exposed outside through the cut slit. Further, since the cut slit is closed by a subsidiary unit, such as a rubber ring, which is readily elastically deformed, the nib is in direct contact with the cut slit and is thereby broken or damaged, and the durability of the writing tool is relatively low. The writing tool is problematic in that the rubber ring is exposed outside the cut slit, so that the rubber ring may be damaged when the rubber ring comes into contact with an external object. Further, the cut slit may become deformed after frequent use of the writing tool, and thus the efficiency with which the nib is sealed may be deteriorated.